Abstract
Usability is considered to be one of the most important quality factors that determine the success/failure in the actual use of an interactive system. This can explain the ever-increasing number of publications addressing the problem of usability evaluation. However, most of these proposals only consider usability evaluations after the application is fully implemented and deployed. Some others are based on reviewing usability principles in intermediate artifacts with regard to their conformance with a set of guidelines. Since the traceability between these artifacts and the final application is not well established, performing usability evaluations by considering these artifacts as input may not ensure the usability of the final application. This problem may be alleviated by using a model-driven engineering (MDE) approach due to its intrinsic traceability mechanisms that are established by the transformation processes. The present paper aims to delineate a method for evaluating usability throughout an MDE development life cycle by considering conceptual models as input. To do this, two main contributions are proposed. The first one, called usability-driven model transformation, aims to ensure that an intermediate artifact with the required level of usability is generated. It controls the model transformation process according to a set of usability attributes. The second contribution, called early usability evaluation, performs the usability evaluation from the conceptual models by defining metrics based on conceptual primitives that constitute the conceptual models. This evaluation would be a significant advantage with regard to saving time and resources. The early usability evaluation is empirically validated by comparing the usability measure obtained by our proposal and the level of usability perceived by the end-users.